How old is "too old" ?

I don't have an informed opinion on a poodle for having a litter. I haven't given it a whole lot of though so the best I can do is an educated guess of maybe 7-ish.
I've never bred one of my girls past age 6 and I've never bred one more than twice. Just how I work it. I'd probably stick to similar rules should I ever find myself breeding poodles of any size, which is unlikely.

As for stud dogs, I don't think there is a limit. If his swimmer swim and he's in good health good for him. Wonder's sire was 10 I believe when we bred to him. Ike just had a litter a year ago and he's 14 (but it was artifically done since he's been neutered for three years lol) Thats kind of the beauty of collecting and storing a stud. A good friend of mine used a stud a couple years ago that had been dead for 5 years. Handy stuff I suppose. Now I would change my mind on age for a stud dog if he were being bred regualry, I'd think that would put a strain on him.

Just so you know the AKC standard;
How old must the sire or dam be in order for a litter to be eligible for registration?

Chapter 3, Section 5 of the Rules Applying to Registration and Discipline reads as follows:
http://www.akc.org/pdfs/rulebooks/RREGS4.pdf
"No dog or litter out of a dam under eight (8) months or over twelve (12) years of age at the time of mating, or by a sire under seven (7) months or over twelve (12) years of age at the time of mating, will be registered unless the application for registration shall be accompanied by an affidavit or evidence which shall prove the fact to the satisfaction of The American Kennel Club."

If you have had a litter registration application form rejected because the age of the sire and/or dam was not in compliance with Chapter 3, Section 5, and you request the AKC to reconsider the matter, you should submit as much information and material as possible.

The AKC would want to know if the breeding that took place was a "planned" breeding. We would also want to know if there were any witnesses to the breeding who are in a position to identify the sire and dam and, if so, statements from those witnesses should be submitted. You should tell us how the bitch was confined during the entire heat period and whether or not there was any possibility of the dam being exposed to any other male during the season in question.

In the case of an overage sire, we would ask whether a veterinarian did a recent sperm count and, if so, that we receive a copy of the veterinarian's findings.

If you own an overage male and you intend to use the dog at stud, we recommend that you have a sperm count done by your veterinarian. If the veterinarian finds that the male is capable of siring a litter you should make several photocopies of his findings, which can then be submitted in the future with applications for litters sired by the dog. We would also recommend that you have a sperm count done every six (6) months thereafter.

After review, the AKC will either accept or reject the application. If accepted, the individual dog registration applications will be mailed to the litter owner.

Hmm, good question. I was just contacted by a breeder I had been speaking to in the fall (she had been planning to breed her two bitches, when one got pyometra and had to have an emergency spay and the other didn't take). As her line will essentially be finished due to this, she decided to lease her friend's bitch who is a descendent of her line (she bred the mother). The bitch just turned 7 in December and this will be her 4th and final litter.

Although I usually think 2 to 3 litters should be the maximum per bitch, I decided I am comfortable with this scenario due to the special circumstances. All my dealings with this breeder have been very positive. Plus it make me very comfortable to possibly get a pup from an older bitch who should have had any health concerns come up by now! It's like she's been proven (she had 5 pups in every previous litter, so has 15 offspring running around). The stud is 7 years old as well, so both parents are of an age where genetic issues should have shown up in both them and some of their offspring...